METALLURGY OE-IEON" AND STEEL.
ference was trifling. In thickness the results on reduction of area are contradictory, there being three cases where the thin bars were superior and four cases where the thick were better. An increase in width or an increase in thickness improves the elongation in the 1£ inches that includes the fracture, but the reduction of area is improved in less measure or not at all. :
Applying the same method of inspection to the records of elongation in full length, the wide' bars were superior in four cases and inferior in three cases, while the thick bars were superior in five cases and inferior in two cases. Thus there seems to be quite a difference between the records of full-length tests and those from 12-inch lengths, so that it is justifiable to conclude that while wider and thicker bars do give greater elongation after fracture, the advantage is confined to the region of the "necking/' and the per-
10 18 17 16 15 I' 13 duress] Abscissas owing Lav -lensftlt.ini of Elongat feet. . onofEyft-: * r,l UUK
Ordlnatei Curve A j Curve B: -per cent L-54,000'to -64,000 to ^ Slongation t, 000 pound 1,000 pound nfulllengt Steel; B«eT Steel; see T tl. ibie xyi-s iWe XVI-R
j ; X • j \l
i ;, 1 i :
6 10 15 ! '20 [ 25 30 3£ id. XVl-B.- — LAW OF iHLOHGATiQtf OP i EYE-BAES
centage of stretch throughout the body of the bar is independent of the'section. If this is true, it'is a most important fact and has a wide application in structural engineering. '
• Since tfere is little,-if any,'difference in the percentage- of•eloiu-